CLERMONT — The nation's leading owner of private membership campgrounds has turned its attention to Florida in a bid to expand its network of resorts for families with recreational vehicles.

Thousands Trails Inc. is set to open its first private RV park in Florida later this month in south Lake County, near Disney World. About six other metropolitan areas, particularly in Southeast Florida, are being considered as sites for new parks.

Members pay a one-time membership fee of about $7,500 and annual dues of about $240 to use the company's campgrounds. The family-oriented parks offer 24-hour security, planned recreational activities, a natural environment and amenities such as swimming pools and lodges.

Before it began an aggressive expansion campaign last year, Thousand Trails owned parks primarily in Western states such as California and Texas. The company crossed the Mississippi River last year, adding 14 new parks in the Eastern.

The company, based in Bellevue, Washington, now has 42 resorts with about 10,000 campsites in 16 states. It also has more than 70,000 members. The company, which opened its first park in 1972, went public in 1979. Assets in 1984 were $269 million, compared with $34.3 million in 1979.

During the past five years, Thousand Trails has tripled its membership, revenue and profit, company executives say. Membership sales accounted for almost 80 percent of the company's revenue last year.

Although the company is slowing development of new parks this year, it will consider new park sites and land acquisitions in Florida through Thousand Trails and Landnet Inc., one of five subsidiaries.

Landnet, created in 1984 to review potential park sites, has expanded into a real estate brokerage for its parent company and other recreational resort developers and investors.

Paul Constantine, president of Landnet, said the company does not have a specific acquisition goal in Florida but is focusing on large markets such as Tampa-St. Petersburg, Jacksonville, Miami and Orlando. Thousand Trails builds its parks within 100 miles of major metropolitan areas.

The average Thousand Trails park is about 200 acres, with fewer camp sites per acre than most RV resorts, the company says.